1. Field of the Invention
This invention relates to a process of nickel plating for forming a plated film having a high phosphorus content, and is applicable to an electrical contact having a sliding portion, an electrical part having a printed circuit board and a soldered portion, and a part for wiring.
2. Description of the Related Art
Japanese Unexamined Patent Publication (KOKAI) No. 248882/1985 discloses a technique relating to this invention. The publication sets forth an electroless plating bath capable of forming an electroless nickel plated film having a high phosphorus content of from 0.20 to 0.25 in atomic ratio of phosphorus with respect to nickel taken as one (1). An electroless plated film formed by using the electroless plating bath has a high phosphorus content of from 0.20 to 0.25 in atomic ratio of phosphorus with respect to nickel taken as one (1), and is superior in chemical resistance and abrasion resistence.
A problem arises, however, in that the electroless plated film formed by using the electroless plating bath cannot be applied to electrical parts having a sliding portion, such as electrical contacts. This is part of the sliding portion should always be subjected to a subsequent soldering process and because the electroless plated film is inferior in wettability with respect to solders.